Even with covering in blankets, I lost 2 scheffleras and a rubber tree to the freeze we had in Austin. How far down should I trim, in hopes these old guys come back?

Happy Holly-days

some items in Texas need more than a sheet.we can add lights to give off heat and give added protection.
I have my zebra plant indoors.its like your 2 cold air or cold draft will drop leaves and damage stem sometimes.If your rubber tree is loseing sap on the stems it got damaged real good.if it wrinkled the stem up to where it gets woody cut back to wood part and watch.it may shoot up a new stem.I've never gown the other.its on my want list.My gardenbook lists low temp of 50s.Cardboard boxes do well also to insulate the cold air.I have an angelwing begonia on my porch.its screened in though and have added plastic& still covered with sheet and placed at porch light so light was under blanket.It only got 4 leaves on the very bottom.I use sheets& fleece blankets.I cover them around 3 so can build some heat.I have some buckets scattered in yard also.Am doing a aloe in ground a baby off shoot.baggie& bucket over it.so far so good.

Was nice out today though in TX.I played compost Queen.